In modern poultry processing plants the poultry or birds are conveyed through the plants in equally spaced relationship on an overhead conveyor in an inverted attitude, with the birds suspended from the conveyor by their feet or hocks. The birds move on the conveyor system through various processing stations where they are stunned, killed, scalded, defeathered, eviscerated, etc.
In the process of killing the birds, it is desirable to cut the jugular vein of each bird without severing the spinal cord or trachea so that the birds tend to bleed to death. With this procedure, the heart of the bird tends to pump the blood from the body of the bird. If the spinal cord is inadvertently severed during the killing procedure, the heart of the bird stops its function and/or the bird is likely to have spasms so as to inhibit further processing of the bird until the spasms subside. If the trachea of the bird should be severed, the blood of the bird is likely to choke the bird before the bird bleeds to death. Thus, it is important to orient the head and neck of the bird during the cutting procedure in order that the neck tissue and jugular vein of the bird be severed without damaging the spinal cord and trachea.
Since the necks and heads of the birds on an overhead conveyor are suspended beneath the bird as the birds move through the processing plant, it is difficult to control the exact positions of the heads and necks because of the differences in size, weight and configuration of each bird and because the conveyor system tends to swing and twist the birds during movement through the processing plant.